Radar signals suggest the Malaysia Airlines flight may have tried to turn back before disappearing (Picture: Malaysian Maritime Enforcement/AFP/Getty Images)

Air safety experts have indicated the missing Malaysia Airlines flight may have been involved in a terrorist incident, as officials confirmed up to four passengers, two with stolen passports, were under investigation.

Fears that a hijacking may be behind the Boeing 777’s disappearance were heightened this morning as Malaysian authorities said they were liaising with the FBI over the suspect passengers, and it was also suggested the flight may have turned back on its journey between Kuala Lumpur and Beijing on Saturday.

‘All the four names are with me and have been given to our intelligence agencies,’ Malaysian transport minister Hishammuddin Hussein said. ‘We are looking at all possibilities.’

It is an agonising wait for the families of the 239 people on board missing Malaysia Airlines flight MH370 (Picture: EPA)

As FBI officials flew out to Malaysia to assist with the investigation, conflicting rumours surrounding the disappeared MH370 flight continued to add to speculation regarding its fate.

David Gleave, an air accident investigator, explained to BBC News that terrorism was a distinct possibility in an incident like this particularly as there was no distress signal from the plane.

However, an anonymous pilot also suggested he heard a mumbled transmission just before the plane’s disappearance although air traffic control have said they received no such communication.

Despite two oil slicks being spotted in the South China Sea yesterday, no crash site has yet been identified.

A widespread search is now underway to find the wreckage of the missing plane, believed to be somewhere in the South China Sea (Picture: Malaysian Maritime Enforcement/AFP/Getty Images)